Average
- If the average age of four children is 12 years and the average age of these children and their father is 20 years, what is the age of the father ?
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Here , The average age of four children = 12 years
Total age of 4 children = 4 × 12 = 48 years
The average age of four children and father = 20 years
Total age of 4 children and father = 20 × 5 = 100 years
&there; Father’s age = Total age of 4 children and father - Total age of 4 childrenCorrect Option: A
Here , The average age of four children = 12 years
Total age of 4 children = 4 × 12 = 48 years
The average age of four children and father = 20 years
Total age of 4 children and father = 20 × 5 = 100 years
&there; Father’s age = Total age of 4 children and father - Total age of 4 children
Hence , Father’s age = (100 – 48) years = 52 years
- The average age of a husband and his wife was 23 years at the time of their marriage. After five years they have a one year old child. The average age of the family now is
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Here , At the time of their marriage , The average age of a husband and his wife = 23 years
After five years they have a one year old child.
Total present age of family = (2 × 23 + 2 × 5 + 1) years
Total present age of family = (46 + 10 + 1) years = 57 yearsCorrect Option: B
Here , At the time of their marriage , The average age of a husband and his wife = 23 years
After five years they have a one year old child.
Total present age of family = (2 × 23 + 2 × 5 + 1) years
Total present age of family = (46 + 10 + 1) years = 57 years
∴ Required average = 57÷3 = 19 years
- Three years ago, the average age of a family of 5 members was 17 years. A baby having been born the average age of the family is the same today. The present age of the baby (in years) is
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Here , Three years ago, the average age of 5 members = 17 years
Three years ago, Total age of the family = 17 × 5 = 85 years
Total age of 5 member family today = 85 + 15 = 100 years
Born on baby , the average age of 6 members = 17 years
Total age of the family with child today = 17 × 6 = 102 yearsCorrect Option: A
Here , Three years ago, the average age of 5 members = 17 years
Three years ago, Total age of the family = 17 × 5 = 85 years
Total age of 5 member family today = 85 + 15 = 100 years
Born on baby , the average age of 6 members = 17 years
Total age of the family with child today = 17 × 6 = 102 years
Age of baby = 102 – 100 = 2 years
- After replacing an old member by a new member, it was found that the average age of five members of a club is the same as it was 3 years ago. The difference between the ages of the replaced and the new members is
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According to question ,
Increase in ages of five members in 3 years = (3 × 5) years = 15 years
As average age remains same,Correct Option: D
According to question ,
Increase in ages of five members in 3 years = (3 × 5) years = 15 years
As average age remains same,
∴ Required difference = 15 years
- The frequency distribution data is given below. If the average age is 17 years, the value of m is
Age (in years) : 8 20 26 29 Number of people : 3 2 m 1
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As per the given details in question , we have
Required average = 8 × 3 + 20 × 2 + 26 × m + 29 × 1 3 + 2 m + 1 ⇒ 17 = 24 + 40 + 26m + 29 6 + m
⇒ 17 (6 + m) = 93 + 26 m
⇒ 102 + 17m = 93 + 26m
Correct Option: A
As per the given details in question , we have
Required average = 8 × 3 + 20 × 2 + 26 × m + 29 × 1 3 + 2 m + 1 ⇒ 17 = 24 + 40 + 26m + 29 6 + m
⇒ 17 (6 + m) = 93 + 26 m
⇒ 102 + 17m = 93 + 26m
⇒ 26m – 17m = 102 - 93
⇒ 9m = 9
⇒ m = 1
